Effects of chemical composition and temperature of heating on the infrared spectra of Li-saturated dioctahedral smectites. (II) Near-infrared region

Clay Minerals ◽  
2000 ◽  
Vol 35 (5) ◽  
pp. 753-761 ◽  
Author(s):  
J. Madejová ◽  
J. Bujdák ◽  
S. Petit ◽  
P. Komadel

AbstractDiffuse reflectance spectra in the near-infrared region are presented for Li-saturated smectites heated up to 200°C. The smectites included three montmorillonites, an Fe-beidellite and a ferruginous smectite. Unheated samples showed a complex band near 7060 cm-1 assigned to the first overtone of the OH-stretching mode of structural hydroxyl groups and bound H2O. The OH combination bands appeared in the 4600-4300 cm-1 region. Spectra of heated montmorillonites showed an upward shift and splitting of the OH-overtone band into two components near 7170 and 7110 cm-1. The presence of a band near 7170 cm-1, assigned to the overtone of the AlMgLiOH-stretching vibration, implied that local trioctahedral domains were created upon Li(I) fixation in the previously vacant octahedral positions of montmorillonites. The OH combination bands were shifted to higher frequencies and a new band appeared near 4472 cm-1 in the spectra of montmorillonites heated to temperatures in excess of 130°C. No features indicating Li(I) in the structure of Fe-beidellite or ferruginous smectite were observed in the NIR spectra.

1985 ◽  
Vol 40 (7) ◽  
pp. 699-705 ◽  
Author(s):  
H.-D. Autenrieth ◽  
B. Kottmann ◽  
S. Kemmler-Sack

By activation of the new host lattice Ca3La2Te2O12 with trivalent rare earth ions an emission in the visible (Ln3+=Sm, Eu, Tb, Dy, Ho, Er, Tm) or near infrared region (Nd, Ho, Er, Tm, Yb) is observed. Energy transfer from Nd3+ to Yb3+ , from Er3+, Yb3+ to Ho3+ and from Yb3+ to Tm3+ has been found to occur. The excitation, emission and diffuse reflectance spectra are analyzed.


1990 ◽  
Vol 116 (1) ◽  
pp. 93-99 ◽  
Author(s):  
Jan Kratochvíla ◽  
Zdeněk Salajka ◽  
Antonín Kazda ◽  
Zbyněk Kadlc ◽  
Jaroslav Souček ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document